Variation and inheritance - B1h

Dominant alleles control the development of a characteristic even if present on only chromosome in a homologous pair. Recessive alleles control the development of a characteristic only if a dominant allele is not present.

1 of 6

What does heterozygous and homozygous mean?

Heterozygous means that your chromosomes contain different alleles of a gene for a particular gene or condition, whilst homozygous means that your chromosomes contain the same alleles of a gene for a condition.

2 of 6

What are dominant and recessive alleles?

Dominant alleles control the development of a characteristic even if present in only one chromosome in a homologous pair. Recessive alleles control the development of a characteristic only if a dominant allele is not present.

3 of 6

What is the cause of inherited diseases and what are some examples?

Inherited disorders, such as cystic fibrosis, sickle cell anaemia and red-green colour blindness, is often due to a faulty recessive allele. This means that the condition can only be inherited if both parents carry the recessive gene.

4 of 6

What causes variation?

Genetic, environmental & a combination of features. A genetic feature is your blood group & eye colour though environmental features include language & scars. Body mass, intelligence & height are because of a combination of genetic and environm

5 of 6

What causes variation?

Genetic, environmental & a combination of features. A genetic feature is your blood group & eye colour though environmental features include language & scars. Body mass, intelligence & height are because of both genetic and environmental features.

Combine this resource with others

Other cards in this set

Card 2

Front

What does heterozygous and homozygous mean?

Back

Heterozygous means that your chromosomes contain different alleles of a gene for a particular gene or condition, whilst homozygous means that your chromosomes contain the same alleles of a gene for a condition.